Microsoft sued the Justice Department in April, claiming that the government’s demands for silence were unconstitutional. The company said that Outlook.com and Office365 were the products most often targeted by the Justice Department, adding that it received 2,576 requests for customer data accompanied by a gag order between September 2014 and March 2016.

In a filing today, the ACLU asked the court to allow it to join the suit. The civil rights non-profit says Microsoft welcomed its intervention, and argued that it is directly impacted by the case because it uses Microsoft products.

“A basic promise of our Constitution is that the government must notify you at some point when it searches or seizes your private information,” Alex Abdo, an ACLU senior staff attorney said in a statement announcing the filing. “Notice serves as a crucial check on executive power, and it has been a regular and constitutionally required feature of searches and seizures since the nation’s founding. The government has managed to circumvent this critical protection in the digital realm for decades, but Microsoft’s lawsuit offers the courts an opportunity to correct course.”

The Justice Department often issues its requests for data under a 30-year-old law called the Electronic Communications Privacy Act (ECPA), which allows for gag orders to be issued along with data requests. Many of the gag orders come without an expiration date, so Microsoft and other cloud storage companies are never allowed to tell customers that their data has been turned over.

In its lawsuit, Microsoft argued that the government is taking advantage of ECPA in order to conduct secret investigations. The Justice Department “has exploited the transition to cloud computing,” Microsoft stated.

A Microsoft spokesperson said the company welcomed the ACLU’s participation in the lawsuit. “We appreciate the support from the ACLU and many others in the business, legal and policy communities who are concerned about secrecy becoming the norm rather than the exception,” the spokesperson said.

A federal district judge will have final say over whether the ACLU is allowed to join the lawsuit.